stream hisense firetv issues

Having issue with the Xfinity Stream app on my new Hisense TV.

Downloaded the app via the embedded FireTV interface. All other apps (Netflix, Prime, ...) are fine. But Stream will occasionally do the following:

1) Audio and video out of sync - need to pause and restart.

2) about once a week Stream will not respond - need to unplug the TV for a "reset"

I did contact HiSense, and ran all of their tests, even doing a factory reset of the TV. Since all other apps work fine, they can't help me anymore.

Read that I may need to use an external device (like a Roku) to use Stream, but that seems excessive.

Anyone else having these problems? Can't just be me!